Existing electronic white boards are interactive or non-interactive: an interactive white board works with a digital projector to display computer display to the white board, making the white board into a super large interactive computer touch screen. A uses can use fingers to click directly on the white board to operate the computer system and at the same time write, draw or modify contents; while the non-interactive white board can not be connected to a computer, in that the content of the white board can only be stored through printing on paper. There are many kinds of interactive white boards: one use electromagnetic conversion technology and its metal pen generate magnetic field with electric current passing through; when moving on the white board, track of the pen can be deduced based on electromagnetic conversion principle, and is converted and recorded as coordinate records; it can provide very precise coordinate. However the cost of materials is relatively high and required special electronic pen, making it not very convenient to use; another one comprises plastic membrane with resistance networks on upper and lower layers; under no pressure, the plastic membrane ensure no short circuit through insulating devices; when writing on the board, upper and lower resistance network short circuit under the pressure, and generate different voltage for different positions on the resistance network, thus defines the position of the moving pen through change of voltage. It does not use special pens, but needs special plastic membrane to capture moving objects. After prolong use, the plastic membrane is subject to scratch, which causes white noise. It is also subject to environment factors such as temperature, humidity, which cause the system become unstable; another one uses supersonic technology, i.e., by adding a special supersonic emitting device on the pen, receivers on left and right top corners of the white board, it calculates the distance between the object and receivers through calculating time difference in emitting and receiving supersonic waves, then use algebra principles to reach the track of the whiting pen. This device needs re-positioning and adjustment before every use and pen must be perpendicular to the writing surface, or errors occur. Special electronic pens not only increase cost, but also make it less convenient; in order to resolve the special requirement for electronic pens and erasers for existing devices, and dependency on special writing surfaces, this invention provides a kind of white board utilizing infrared beams to capture inputs, but because in traditional infrared touch systems or touch screen technologies, there is limitation on physical dimensions of electro-optical devices such as emitting and receiving diodes, if position of moving object is decided by only replying on whether beams of emitting and receiving diodes on identical light axis is block or not, the maximum resolution of applied white board is the dimension of the emitting or receiving diode. Due to its low resolution, this type of technology can apply only to applications requires touching only, but not to hand writing input methods. In order to improve resolution of touch screens, some latest most typical patented technologies were published. U.S. Pat. No. 6,429,857 dated Aug. 6, 2002 publicized a kind of off axis single emitting multiple receiving technology, wherein judgments are based on not only whether a light beam is blocked for emitting and receiving tubs on the same light axis, but also on off axis blocking using adjacent emitting and receiving diodes. Even though this technology can improve resolution for a certain level, dead corners caused by physical distribution density of infrared diodes and complexity of calculation can cause some errors, which in turn cause problems in uniformity of resolution and smoothness in capturing objects. The Chinese patent 00121462.4 dated Feb. 13, 2002 publicized a kind of method and structure to improve performance of infrared touch screens. It uses the lowest point of a hyperbolic model as the coordinate of the blocking object. This invention claims that when an object is blocking, output voltages of several blocked diodes forms a hyperbola, by assuming only when the dimension of the blocking object is similar to that of a finger, and variation of output voltages on receiving diodes of all channels must fit into changing trend of said hyperbola, an effective touching event happens, or a precise coordinate is decided. If the blocking object is a 2-5 mm pen head or an object cannot act like a finger, through which an infrared beam can pass, or the infrared beam fro the emitting diode cannot reach the blocked receiving diode through secondary reflection, said hyperbolic judgment method no longer stands. This shows that it is not enough to just copy the current infrared touch screen capturing technologies to electronic white boards to capture tracks (or characters) of moving objects on white boards.